Power BI Desktop sign-in fails with HTTP 404 / WAM NoNetwork error (Browser sign-in works)

[MostafaEs]

Hello,

I am unable to sign in to Power BI Desktop, and I would appreciate your assistance. The issue is consistent and reproducible, and I have already completed extensive troubleshooting.

Important clarification:
I can successfully access and sign in to Microsoft authentication and Power BI services via a web browser, including:

https://login.microsoftonline.com

https://app.powerbi.com

However, Power BI Desktop fails to sign in with an authentication error. This confirms that my account, credentials, and tenant are valid, and that the issue is specific to Power BI Desktop authentication, not the web service or the user account.

When attempting to sign in to Power BI Desktop, I receive the following errors:

“We can’t connect you”

HTTP 404

Endpoint: login.microsoftonline.com

WAM Error Code: 3399680404

Error Message: NoNetwork

This occurs even though internet connectivity is working normally.

Environment details
Power BI Desktop version: 2.150.2102.0 (64-bit, January 2026)

Operating systems tested: Windows 10 & Windows 11 (tested on two separate devices)

Account type: Work / organizational account

The same HTTP 404 authentication error occurs on both machines, including a newly installed Windows 11 device.

Troubleshooting steps already completed
Verified Power BI Desktop is fully up to date.

Cleared Power BI cache and local data.

Changed authentication setting to "Use default web browser."

Disabled Windows Web Account Manager (WAM) via registry (DisableWAM = 1).

Reset Windows network stack (DNS flush, Winsock reset).

Enabled Power BI Desktop tracing and reviewed the files.

Tested on a different network and different hardware — the error persists.

Additional observations:
The failure occurs specifically during the Desktop app's authentication phase (WAM/MSAL interaction), suggesting a potential conflict with network security components, proxies, or SSL/TLS inspection, despite successful browser-based login.

I would appreciate guidance on:

Whether this is a known issue with the current Power BI Desktop version.

Specific Microsoft identity endpoints that must be bypassed in network inspection.

Any additional diagnostics or logs you require (I have trace files ready to share).

Thank you for your assistance.

Kind regards,
Mostafa

[v-shchada-msft]

Hi @MostafaEs,

Just checking in to see if your issue has been resolved. Please let us know if you need any further assistance.

Thank you.

[v-shchada-msft]

Hi @MostafaEs,
Thank you for reaching out to the Microsoft Fabric Community Forum.

Just checking in, were you able to resolve the issue? If not, please feel free to share an update and we'll be happy to assist further.
Your feedback will also help others facing similar challenges.

Thank you.

[v-shchada-msft · Accepted solution]

Hello @MostafaEs,
Thank you for posting your query in the Microsoft Fabric Community Forum.

Power BI Desktop sign‑in errors with HTTP 404 / WAM NoNetwork usually happen because the Desktop app uses a different authentication flow than the browser. While browser sign in works through standard HTTPS, the Desktop client relies on WAM/MSAL and the Edge WebView2 runtime. If a proxy, firewall or SSL/TLS inspection interferes with those requests or if TLS 1.2+ isn’t fully enabled, the Desktop app can fail even when browser logins succeed. That’s why you’re seeing the error consistently across machines and networks.

Please confirm that WebView2 is installed and updated, ensure TLS 1.2 or higher is enabled system wide and check that no proxy or security appliance is intercepting traffic to Microsoft identity endpoints like login.microsoftonline.com. If inspection is unavoidable, those endpoints need to be whitelisted or bypassed so the authentication flow remains intact. 

Please refer to the Microsoft documentation:
Troubleshoot sign-in issues in Power BI Desktop - Power BI | Microsoft Learn
https://learn.microsoft.com/power-bi/connect-data/desktop-troubleshooting-sign-in
Power BI Security - Microsoft Fabric | Microsoft Learn
Enabling Microsoft Edge (Chromium) for OAuth authentication in Power BI Desktop - Power Query | Micr...

I hope this information helps. Please do let us know if you have any further queries.

Thanks and Regards.

[DanieleUgoCopp]

Hello,

I’m not completely sure, but since the issue happens on multiple machines and browser sign-in works fine, it sounds more related to WAM/MSAL or something in the network/security layer blocking Desktop authentication specifically.  Another thing you could try is installing an older Power BI Desktop version to see if it’s tied to the January 2026 release.

Best regards,
Daniele